Apache HTTP Server Version 1.3

Module mod_so

This module is contained in the mod_so.c file. It is
compiled in by default on Windows and is not compiled in by default on
Unix. It provides for loading of executable code and modules into the
server at start-up or restart time. On Unix, the loaded code typically
comes from shared object files (usually with .so
extension), whilst on Windows this module loads DLL
files. This module is only available in Apache 1.3 and up.

In previous releases, the functionality of this module was provided
for Unix by mod_dld, and for Windows by mod_dll. On Windows, mod_dll
was used in beta release 1.3b1 through 1.3b5. mod_so combines these
two modules into a single module for all operating systems.

Summary

This is an experimental module. On selected operating systems it can be used
to load modules into Apache at runtime via the Dynamic
Shared Object (DSO) mechanism, rather than requiring a recompilation.

Directives

The LoadFile directive links in the named object files or libraries
when the server is started or restarted; this is used to load
additional code which may be required for some module to
work. Filename is either and absolute path or relative to ServerRoot.

The LoadModule directive links in the object file or library filename
and adds the module structure named module to the list of active
modules. Module is the name of the external variable of type
module in the file. Example (Unix):

LoadModule status_module modules/mod_status.so

Example (Windows):

LoadModule status_module modules/ApacheModuleStatus.dll

loads the named module from the modules subdirectory of the
ServerRoot.

The Apache module API is unchanged between the Unix and Windows
versions. Many modules will run on Windows with no or little change
from Unix, although others rely on aspects of the Unix architecture
which are not present in Windows, and will not work.

When a module does work, it can be added to the server in one of two
ways. As with Unix, it can be compiled into the server. Because Apache
for Windows does not have the Configure program of Apache
for Unix, the module's source file must be added to the ApacheCore
project file, and its symbols must be added to the
os\win32\modules.c file.

The second way is to compile the module as a DLL, a shared library
that can be loaded into the server at runtime, using the
LoadModule
directive. These module DLLs can be distributed and run on any Apache
for Windows installation, without recompilation of the server.

To create a module DLL, a small change is necessary to the module's
source file: The module record must be exported from the DLL (which
will be created later; see below). To do this, add the
MODULE_VAR_EXPORT (defined in the Apache header files) to
your module's module record definition. For example, if your module
has:

module foo_module;

Replace the above with:

module MODULE_VAR_EXPORT foo_module;

Note that this will only be activated on Windows, so the module can
continue to be used, unchanged, with Unix if needed. Also, if you are
familiar with .DEF files, you can export the module
record with that method instead.

Now, create a DLL containing your module. You will need to link this
against the ApacheCore.lib export library that is created when the
ApacheCore.dll shared library is compiled. You may also have to change
the compiler settings to ensure that the Apache header files are
correctly located.

This should create a DLL version of your module. Now simply place it
in the modules directory of your server root, and use
the LoadModule directive to
load it.